Process for the isolation of polymer fractions

ABSTRACT

The invention relates to a process for isolating, from a polymer comprising repeating units which are individually of Formula X                    
     in which 
     Y is P or N, 
     Ar 1  &amp; Ar 2  are bivalent aromatic groups, 
     Ar 3  is a monovalent aromatic group, and 
     the units of Formula X may be the same or different, 
     a molecular weight fraction which is especially suitable for use as a charge transport material.

This application is the National Phase of International ApplicationPCT/GB00/02310 filed Jun. 14, 2000 which designated the U.S. and thatInternational Application was published under PCT Article 21(2) inEnglish.

The present invention relates to certain polymeric materials, andcompositions containing them which are charge transport materials. Theinvention also relates to processes for making these polymers and theiruse in devices such as electroreprographic devices andelectroluminescent devices.

Polymers of the invention may be used in the field ofelectroreprography. Electroreprography is any process in which an imageis reproduced by means of electricity and incident radiation, usuallyelectromagnetic radiation, more usually visible light.Electroreprography includes the technology of electrophotography whichencompasses photocopying and laser printing technologies. Typically, inboth a photocopier and a laser printer, a photo-conductive member isfirst charged in the dark (e.g. by applying a high voltage via a Coronadischarge). Then a latent electrostatic image in charge is produced bypartial exposure of the charged photo-conductive member (e.g. a drum orbelt) to radiation (e.g. light). The radiation neutralises the charge inthe exposed regions. The light source can either be reflected light froman illuminated image (photocopying) or from a laser which scans thephoto-conductive member usually under instruction from a computer (laserprinting). Once a latent image has been produced in charge, it isdeveloped with toner, the toner is transferred onto a substrate (e.g.paper) and then fixed thereto (e.g. by heat) so that a visible image isobtained.

The photo-conductive member typically comprises a photo-conductor (e.g.an organic photo-conductor [“OPC”]) which must perform two differentfunctions: generate a charge on exposure to the incident radiation; andtransport the photo-generated charge to the surface. The unexposedregions of the photo-conductive member will retain their charge and formthe latent image. It is usual to use different materials for each ofthese two processes and develop materials which are separately optimisedfor their ability to generate photo-induced charge (charge generatingmaterials or “CGMs”) or their ability to transport charge (chargetransport materials or “CTMs”). The photo-conductor can be constructedas a single layer or from a plurality of layers, for example from atleast one charge generating layer (“CGL”) comprising the CGM and atleast one separate charge transport layer (“CTL”) comprising the CTM.

An ideal photoconductor would be one where the material charges rapidlyto a high value in the dark, retains the charge in the dark (i.e.exhibits no dark decay) and shows rapid total discharge on exposure tolow-intensity illumination. The time taken for the charge-dischargecycle of a photo-conductor limits the maximum speed at which the latentimage can be generated. Photo-conductive materials with improvedelectrical properties may allow faster printing and copying and/orhigher quality copies and/or longer component life.

The applicant has discovered means to improve the charge transportproperties of certain polymers based on triaryl amine repeat unit(s).

PCT/GB98/03685 is a co-pending patent application which describes novelCTM polymers of repeat unit of Formula D

where Y¹ is N, P, S, As and/or Se and Ar¹, Ar² and Ar³ are aromaticgroups. These polymers are prepared by the addition of an end cappingreagent to control the molecular weight of the final polymer and henceits desirable properties as a CTM.

The disclosure of this co-pending application is incorporated herein byreference; its definitions and description should be used in connectionwith the present invention except as modified herein.

The procedure of the co-pending application produces attractive chargetransfer agents. However we have now found that they may be furtherimproved and indeed similar-materials which are not end capped may beimproved by isolating an appropriate molecular weight fraction fromthem. We have found that medium molecular weight. polymers are generallysuperior to lower and higher molecular weight polymers derived from thesame starting materials; lower molecular weight polymers are lesseffective and crystallise more readily and are thus not durable; highermolecular weight polymers are durable but less effective. By means ofthis invention a fraction may be selected which is of good performanceand is sufficiently durable to cover the required life of components ofelectroreprographic devices whilst optimising its charge transporteffectiveness.

According to one aspect of the present invention there is provided aprocess which comprises isolating, from a polymer comprising repeatingunits which are individually of Formula X

in which

Y is P or N,

Ar¹ & Ar² are bivalent aromatic groups,

Ar³ is a monovalent aromatic group, and

the units of Formula X may be the same or different,

a molecular weight fraction which is a charge transport material.

According to a another aspect of the present invention there is provideda process in which an improved charge transport material is produced byisolating, from a first charge transport material which is a polymercomprising repeating units which are individually of Formula X

in which

Y, Ar¹, Ar² and Ar³ are as previously defined; and

the units X may be the same or different,

a molecular weight fraction of improved charge transport properties.

Ar¹ Ar² and Ar³ preferably comprise benzenoid rings which are optionallyfused with other, preferably benzenoid, rings and/or substituted.

The polymer may be a block copolymer comprising such repeat units.

Trivalent repeat units of Formula D may be included to permit a degreeof chain branching if desired.

The molecular weight fraction produced by the process according to thepresent invention may be of Formula 1:

AX_(m)B  Formula 1

in which

each X is a unit of Formula X as defined above and may be the same ordifferent;

A and B are chain terminating groups, for example, hydrogen, chlorine,bromine or iodine, or other leaving groups used in a polymerisationprocess by which the polymer is made, or end capping groups, and

m is the average number of X units per molecule of the fraction.

The value of m is suitably 4 to 50, preferably 4 to 30, more preferably4 to 25 for example 4 to 15 and especially 5 to 13 or 6 to 14. Generallyit is desired that m is at least 5 in all of the above ranges.

The polydispersity of the fraction is suitably 1.1 to 4, preferably 1.1to 3 and more preferably 1.2 to 2.5. Suitably the fraction issubstantially free from molecules having 3 or fewer or 50 or more repeatunits.

The aryl groups may be mono- or poly-cyclic and the rings are preferablybenzene rings substituted with, for example, one or more C₁₋₄₀-alkylgroups in order to increase their solubility in for exampletetrahydrofuran (THF) for processing purposes. They may have fused ringgroups, naphthyl groups or covalently linked benzene rings for examplebiphenyl residues but are preferably benzene rings which are eachsubstituted with alkyl groups providing a total of one to eightaliphatic carbon atoms per benzene ring.

Preferably the groups A and B are inert to coupling with furthermolecules of the polymer so as to reduce the likelihood of furthergrowth of molecules to undesired sizes. Thus it is preferred that theyshould not be halide atoms.

Molecular weight fractions produced by the present invention may beisolated from polymers prepared without the addition of a separate endcapping reagent to control the molecular weight of the polymer.

Isolation of the molecular weight fraction may be by filtrationtechnologies, chromatographic techniques, osmotic methods, and/or solidextraction using a suitable solvent, for example Soxhlet extraction.

In a preferred form of the invention (which may be used together withone or more of the above techniques) the process comprises a step ofpartially precipitating from a solution of the polymer in a suitablesolvent, a molecular weight fraction thereof. It may be separated bydissolving the polymer in the solvent, precipitating a least soluble(highest molecular weight) fraction and then recovering a fraction ofgreater solubility having good CTM properties, for example inelectrophotographic applications, from the remaining solution. The leastsoluble fraction may be usable as a CTM in non-electrophotographicapplications. Examples of suitable solvents are dichloro- andtrichloro-ethane, dichloro- and trichloro-ethylene, dichlorobenzene,toluene, dioxane and, more preferably, THF. It will be appreciated thatit is not necessary to use any other isolation procedure in conjunctionwith this preferred form of the invention.

If there are undesired low molecular weight molecules present, they maybe allowed to remain in the solution when a desired fraction isrecovered. The fractions may be recovered by

(a) cooling the solution and collecting successive fractions in thecourse of cooling, or

(b) evaporating solvent from a solution of the polymer and collectingsuccessive fractions or

(c) more conveniently, differential precipitation, that is, by theaddition of a precipitant to a solution of the polymer and collectingsuccessive fractions at increasing concentrations of the precipitant, inwhich a precipitant is suitably a liquid which is miscible with thesolvent but in which the polymer is sparingly soluble.

The precipitant may be selected from n-octane, heptane, n-hexane,cyclohexane, methylpentane, n-butanol, n-propanol, 2-propanol, ethanol,methanol, acetone, mixed alkanes such as petroleum ether (pet ether)with boiling range 60-80° C., methyl-t-butyl ether (MTBE), high boilingmixed alkanes such as those available under the trade name Isopar (e.g.Isopar G with a boiling point of about 160° C.); and/or mixturesthereof. The chosen precipitant has a boiling point (at ambientconditions) preferably from about 50° C. to about 200° C., morepreferably from about 60° C. to about 170° C. It is preferably a loweralcohol, for example a C₁₋₆-alkanol, such as ethanol or propanol or,more preferably, methanol, or a lower alkane or cycloalkane, preferablya C₄₋₁₀-alkane or cycloalkane, or acetone. An especially preferredprecipitant is methanol.

The molecular weight fraction collected by the isolating meanspreferably has an average number of repeat units (‘m’ number) of fromabout 4 to about 15, more preferably from about 5 to about 13.

The isolated molecular weight fraction preferably has a much narrowermolecular weight distribution than the crude polymer.

According to a further aspect of the present invention thepolymerisation may be performed in the presence of a controlling meansto control molecular weight of the polymeric material duringpolymerisation (and before isolation) to provide a polymer suitable foruse as a charge transport material, more preferably which iselectroreprographically effective, most preferably with an averagenumber of repeat units ‘m’ of between about 4 and about 25. The meansfor controlling MW may be any of those described in co-pending Britishpatent Application No 9914164.1 (the priority of which is claimed forthis application) and/or those described in co-pending applicationPCT/GB98/03685.

However, even if the crude polymer is already effective for use as a CTMafter polymerisation and without isolation, because a means to controlmolecular weight has been used to prepare the polymer, the isolationmeans according to the aforementioned aspects of the present inventionmay be used to isolate a fraction having further improved properties asa charge transport material. Alternatively, the isolation means may beused to convert crude polymer which is not especially fit for thispurpose into an effective charge transport material. Thus, thecombination of the two methods of control of molecular weight duringpolymerisation and isolation of molecular weight fraction from the crudepolymer after polymerisation can be used flexibly to achieve costeffective production of polymer with the required performance as acharge transport material. The polymeric materials of the presentinvention are preferably obtained by polymerisation controlled byaddition of at least one end capping reagent in an amount sufficient toreduce substantially further growth of the polymer chain. The end cappedpolymers of the invention can be produced more cheaply and with a bettercontrol over their resultant properties (such as their molecular weightand polydispersity) due to the end capping. Furthermore the chemicalnature of the end cap can be selected to control aspects of thepolymerisation and hence properties of the resultant polymer. Forexample carrier mobility, polymer compatibility, electronicconfiguration [e.g. frontier orbital (FO) energy levels] and/orsolubility may be affected by substitution (if used) and/or molecularweight (e.g. mobility can be shown to increase with polymer molecularweight).

For optimum electroreprographic performance preferably the polymers ofthe invention are substantially free of chlorine, more preferablysubstantially free of chloro, bromo and iodo, containing species.

Polymers of the present invention preferably have a weight averagemolecular weight (M_(w)) from about 1000 to about 13000 daltons.

In Formulae 2 and 3 hereinafter a suitable terminal group such ashydrogen or another substituent which is inert to coupling under theconditions of polymerisation, eg an akyl or aryl group, can be selectedto control aspects of the polymerisation and Ar¹, Ar² and Ar³ are eachan optionally substituted aromatic group which may be a mononucleararomatic group or a polynuclear aromatic group. A mononuclear aromaticgroup has only one aromatic ring, for example phenyl or phenylene. Apolynuclear aromatic group has two or more aromatic rings which may befused (for example napthyl or naphthylene), individually covalentlylinked (for example biphenyl) and/or a combination of both fused andindividually linked aromatic rings. Preferably each Ar¹, Ar² and Ar³ isan aromatic group which is substantially conjugated over substantiallythe whole group.

Polymers of the present invention may be made by a polymerisationprocess which is controlled to limit further growth of the polymerchain. If the end capping reagent is generated in situ in excess (e.g.at the step when it is desired to terminate polymerisation) furthergrowth of the polymer chain (and/or polymer network if the is polymer isbranched and/or cross-linked) can be substantially inhibited (e.g.substantially quenched). The end capper adds terminal group(s) to thepolymer chain which are substantially incapable under the conditions ofpolymerisation of undergoing coupling (e.g. with other polymer precursorand/or other parts on the polymer chain). The terminal group(s) end capthe polymer chain and act to substantially reduce the possibility of(preferably stop) further polymerisation by blocking sites at which thepolymer chain could otherwise grow under the conditions of thepolymerisation. Preferably in the polymers of the present invention fromabout 60% to substantially all of the polymerisation sites are blockedby at least one terminal substituent. More preferably (in one option)substantially all such sites are blocked. In another more preferableoption from about 60% to about 90% of these sites are blocked.

Optional features of polymer fractions of the present invention, whichmay further distinguish them from known polymers, are that they can, ifdesired: comprise terminal group(s) other than a group selected from H,halo, hydroxy, glycidyl ether, acrylate ester, methacrylate ester,ethenyl, ethynyl, vinylbenzoxyl, maleimide, nadimide, triflurovinylether, a cyclobutene, a group forming part of a cyclobutene group, andtrialkylsiloxy; and/or be other than copolymer(s) which consist oftriarylamine repeat unit(s) and C₄₋₇alicyclic repeat unit(s) optionallycontaining heteroatom(s); and/or be substantially undoped; and/orsubstantially polydisperse and/or other than of formula:

wherein n is from 7 to 11.

Polymer fractions of the invention preferably comprise at least 4, andmore preferably at least 6, repeat units of Formulae X or 1 or Formulae2 or 3, hereinafter.

Preferred polymer fractions of the present invention comprise moleculesrepresented by Formula 2:

wherein

Ar¹, Ar², Ar³ & Y represent, independently in each case, those atom(s)and/or group(s) as described herein;

n represents an integer from 3 to about 500;

R¹ & R² represent, independently, a terminal group as described herein.

In Formulae X and/or 2, Ar¹, Ar², and Ar³ are preferably, eachindependently, optionally substituted aromatic groups, more preferablyhaving optionally substituted heterocyclic and/or benzenoid rings. Mostpreferably the optionally substituted aromatic groups Ar¹ and Ar² are,or form part of, bivalent C₆₋₄₀-hydrocarbyl groups, preferably phenyleneand/or naphthylene groups. Any substituents are preferably C₁₋₁₅-alkylgroups.

Polymeric material of the present invention may comprise moleculesrepresented by Formula 3

wherein

R¹ & R² represent terminal groups which are unreactive groups, that isare substantially incapable of undergoing chain extension under theconditions of polymerisation;

a & b represent, independently in each case, 0 or an integer from 1 to4;

c represents, independently in each case, 0 to 5;

n represents an integer from 4 to about 200; and

R⁴, R⁵ & R⁶ represent, independently in each case, optionallysubstituted C₁₋₁₅alkyl groups and/or one or more other substituents.

The terminal groups (which may be attached to the repeat units ofFormula X, denoted by A & B in Formula 1 and denoted by R¹ & R² inFormulae 2 and 3 are preferably unreactive groups, that is aresubstantially incapable of undergoing chain extension or cross-linkingunder the conditions of polymerisation. They are more preferablyindependently selected from hydrogen or C₁₋₄₀-hydrocarbyl groups,preferably selected from C₁₋₃₀-alkyl, C₆₋₃₆-aryl and C₇₋₃₆-aralkylgroups, any of which may optionally be substituted. Especially preferredterminal groups comprise C₆₋₃₆-aryl groups optionally substituted withat least one C₁₋₄-alkyl, C₁₋₄-alkoxy, or amino group (itself optionallyN-substituted by at least one C₁₋₄-alkyl). In particular the terminalgroup may be selected from phenyl, optionally substituted with at leastone methyl, 2-methylprop-2-yl, methoxy, ethoxy, trifluoromethyl and/ordiethylamino group.

The novel polymer fractions of the present invention are of use as CTMsin electroreprographic devices. However such polymers may have manyother uses which may rely on the same, similar and/or differentproperties to those required for electroreprography.

For example the polymers of the present invention may be generallyrelevant for use in (and/or in combination with) any application and/ordevice which requires the use of polymeric conductors, polymericphoto-conductors, organic photo-conductors (OPCs), electroluminescent(EL) materials, polymeric materials which exhibit substantialconjugation over the polymer and/or polymeric semiconductors. Preferredpolymeric semiconductors have hole mobilities greater than 0.01cm²/volt.sec. This minimum mobility is either that of the pure polymericmaterial, or of an admixture of the polymeric material with one or moreother polymeric or monomeric materials having different electricaland/or physical properties. Preferably the polymers of the presentinvention also exhibit some or all of the following other usefulproperties: high carrier mobility, compatibility with binders, improvedsolubility, high durability and/or high resistivity undoped.

The polymers of the invention may be used in at least one of the devicesand/or for at least one of the applications described in co-pending PCTapplication GB98/03685.

Certain of these applications may require tuning of the properties ofthe polymers of the invention. For example polymeric CTMs of theinvention when optimised for use with organic light emitting materials(OLEMs) preferably may have a higher molecular weight and/or differentmobilities than are optimal for electroreprography.

Furthermore the compositions and/or specific polymers used for eachapplication may be different. For example it is desirable that anelectroreprographic polymeric CTM is compatible with the binder polymers(such as polycarbonates) used to make a CTL. By comparison a polymericCTM for use in an OLEM may be formulated without many other (or even noother) ingredients to make a film of substantially pure CTM. Thus eachof these CTM polymers may require different physical properties.

The invention is illustrated by the following Examples. Unless indicatedto the contrary, or clearly different from the context, all referencesherein and in the following examples and experiments to percentagesrefer to the percentage by mass of ingredient to total mass of thecomposition to which the ingredient is to be added or of which it is apart.

The number average molecular weights (M_(n)) quoted in the Examplesherein were determined by gel permeation chromatography (Waters 150CV)calibrated against polystyrene standards. Samples were run intetrahydofuran (hereinafter “THF”) using two “Polymer Labs. Mixed D” gelcolumns at a rate of 1 ml/min. A value for M_(n) was determined from theGPC spectrum, and from the M_(n) value, an approximate average degree ofpolymerisation (≡m as defined herein) was calculated by subtracting themass of the terminal groups and dividing by the molecular weight of therepeat unit.

The electrical properties given in the Examples herein were obtained inthe following test methods.

Test Method—Time of Flight (TOF) Experiment to Measure Carrier Mobility

A number of electrophotographic photoreceptors were prepared asdescribed below.

Preparation of Charge Generation Laver (CGL)

Titanyloxy phthalocyanine (TiOPc) type IV (15.0 g) was dispersed into a5% w/w solution of polyvinyl butyral (PVB) in n-butyl acetate (75.0 g)using a high shear mixer. A further quantity of n-butyl acetate (20.0 g)was added to the dispersion to reduce its viscosity. The resultingslurry was charged to an Eiger Mini 50 Motormill (supplied by EigerTorrance Ltd.) containing a charge (34 ml) of 0.6 to 0.8 mm zirconiabeads. The mill was operated at 3,000 rpm for 50 minutes. PVB solution(25.0 g, 5% w/w in n-butyl acetate) was added to the millbase andmilling was continued for a further 10 minutes. The millbase wasdischarged into a receiving vessel and PVB solution (61.5 g) was addedto the mill and circulated for 5 minutes. The solution was thendischarged into the millbase which was stirred throughout to preventpigment agglomeration and n-butyl acetate (349.0 g) was flushed throughthe bead mill and out into the stirred dispersion to yield a CGL coatingformulation of PVB (1.48%), TiOPc (2.75%) and n-butyl acetate (95.77%).

The dispersion was coated onto aluminised Melinex film using a K#2 barand K Control coater model 202 (supplied by RK Print-Coat IndustriesLtd.). The coating was dried for 5 minutes at 100° C. to produce a CGLwhich was approximately 0.4 μm thick.

Preparation of a Charge Transport Layer (CTL) of the Invention

A formulation comprising a CTM of the invention was prepared using anamount of a CTM and (optionally) another CTM as specified in theExamples. If not otherwise specified herein 0.5 g of CTM was used(equivalent to 25% CTM in the CTL) in the following preparation. Thepolymeric CTM and polycarbonate resin (1.5 g of the PCZ availablecommercially from Esprit Chemical Co. under the trade designation TS2020) were dissolved in toluene (7.1 g). This solution was coated on topof the CGL made as described above, using a 150 μm wet film depositingbar and K Control coater. The coating was dried for 90 minutes at 100°C. to give a CTL which was approximately 25 μm thick.

Electroding

A semi-transparent metal electrode was applied to the top of a sectionof the film by vacuum deposition. The CTL thickness was measured usingan Elcometer E 300 device. A small portion of the CGL and CTL (preparedas described above) close to the top electrode, was removed with asuitable solvent to reveal the bottom electrode. The electrodes wereconnected to a power supply and a digitising oscilloscope.

Hole Carrier Transit-time Measurement

The time of flight (TOF) technique is a transient photoconductivityexperiment well known to those skilled in the art. A field was appliedacross the sample via the electrodes and a sheet of charge carriers(holes) was photogenerated at one side of the film. The charge carriersdrifted through the film under the influence of the field creating acurrent which was detected using a current amplifier connected to theoscilloscope. When the carriers reached the counter electrode, thecurrent was observed to decrease and the transit-time across the filmcould thereby be determined from the transit waveform. The measurementwas repeated with a range of different applied voltages.

Determination of Field Mobility (μ)

The drift mobility of carriers (μ) was calculated for each applied field(=V/L) using the equation:

μ=L ² V ⁻¹ t _(tr) ³¹ ¹,

where L is the device thickness, V is the applied voltage and t_(tr) isthe transit time. Mobility at a field strength of 160 kV/cm wasdetermined by interpolation of the mobility vs F plot. A field strengthof 160 kV/cm is typical of what may be present in a workingphotoreceptor. A high value of mobility is desirable because itindicates that the photoreceptor will discharge rapidly on exposure tolight.

Test Method—Photoinduced Discharge (PIDC) Test for Photosensitivity ofOPC Devices

A number of electrophotographic photoreceptors were prepared as in theTOF technique described herein. A photoreceptor test piece ofapproximately 5×10 cm was cut out from the coated aluminised Melinex.The test piece was then fixed to a bare aluminium drum (used as thesubstrate for an OPC), 30 mm in diameter. Two small areas of coatingwere removed from the edge of the test piece using a suitable solvent.The test piece was then electrically connected to the drum using asuitable conductive paint. The drum was then mounted in a QEA PDT 2000device (available commercially from Quality Engineering Associates Inc.Burlington Mass. 01803 USA) and was grounded via the contact in the QEAinstrument. The QEA PDT 2000 was fitted with a 780 nm band pass filter.A track with a consistent −800 V charge of at least 10 mm length wasselected using the charge scanner. Once the track had been selected thePIDC was measured in the known manner. The energy required to dischargethe photoreceptor to ⅛th of its original potential i.e. from −800 V to−100 V (E_(⅞))and the residual potential on the photoreceptor after thehighest energy exposure (˜3 μJcm⁻²) (Vr) were recorded. Low values forE_(⅞) and V_(r) are desirable in a photoreceptor as they indicateefficient discharge of the device on exposure to light.

Photoreceptors With CTMs of the Invention and Various CTL Binders

OPC devices can be prepared in a similar manner to the method describedabove using different CGLs, binders and/or additives in combination withother CTMs and CGMs, for example as described in co-pending applicationPCT/GB98/03685 (e.g. in the tables thereof.

In the following Examples, polymers having repeat units of the typerepresented by Formula X, in which Ar¹, Ar² and Ar³ comprise benzenerings, are identified by the substituents on Ar³ in each repeat unit(e.g. “3-methyl polymer” refers to a polymer having aN-(3-methylphenyl)-diphenyl-4,4′-yleneamine) repeat unit.

EXAMPLE 1 Part A

Preparation of ‘2,4-dimethyl’ polymer by polymerisingbis(N-chlorophenyl)-2,4-dimethylphenylamine without the use ofendcapping reagent and no isolation.

A reaction flask (500 mL, 5 neck) equipped with overhead stirrer,thermometer and nitrogen line was flame dried under nitrogen. Nickel(II)chloride (0.14 g, 1.05 mmol), zinc powder (8.9 g, 136.1 mmol),2,2′-dipyridyl (0.25 g, 1.58 mmol), triphenylphosphine (2.76 g, 10.5mmol) and N,N-dimethylacetamide (anhydrous, 100 mL) were charged to thereaction vessel. The mixture was stirred at room temperature for 1 hourafter which time a deep red/brown solution was observed indicative ofcatalyst formation. The temperature was then raised to 80° C. andbis(4-chlorophenyl)-2,4-dimethylphenylamine (15.0 g, 43.8 mmol) wasadded to the reaction flask. Heating was continued at 80° C. for 6hours, after which time the reaction was deemed complete. The reactionmixture was allowed to cool to room temperature and added to a stirringmixture of water (400 mL) and dichloromethane (400 mL). With stirringHCl (conc., 50 mL) was added dropwise to destroy the excess zinc. Theresulting mixture effervesced. The organic extract was collected and theaqueous phase was further extracted with dichloromethane, with warming,to aid dissolution of some retained product. The dichloromethane phasewas filtered, the organic extracts combined and concentrated underreduced pressure to yield a yellow gum. The resulting gum was dissolvedin THF (400 mL) and precipitated from ethanol (600 mL). The resultingprecipitate was collected by vacuum filtration. The solid was dissolvedin fresh DCM (200 mL) and washed with Na₂CO₃ (1M, 200 mL). The organicextract was collected, concentrated under reduced pressure and purifiedby column chromatography (silica gel), eluting with a 750 mL mixture ofdichloromethane and hexane (in a respective volume ratio of 3 to 1).Removal of the solvent under reduced pressure followed by precipitationfrom THF (200 mL) and methanol (600 mL) yielded the title polymer (Solid1A) as an off-white solid (8.6 g), which was characterised as follows:

M_(n)=3,100 daltons; and m=11.5

The mobility of Solid 1A was measured as described in the Test Methodherein and μ=9.0×10⁻⁶ cm²V⁻¹s⁻¹ (@160 kV/cm).

Part B

Fractionation of ‘2,4-dimethyl’ polymer from polymerisation ofbis(N-chlorophenyl)-2,4-dimethylphenylamine without the use ofendcapping reagent.

Solid 1A (from Part A) was fractionated to obtain material of lowermolecular weight. Solid 1A (6.2 g) was dissolved in dichloromethane (50mL) and hexane (65 mL) slowly added until a gum-like residue formed onthe glassware. The liquor was decanted and concentrated under reducedpressure to yield a pale yellow solid. The resulting solid was dissolvedin THF (50 mL) and precipitated from methanol (400 mL). The resultingprecipitate was collected by vacuum filtration and dried under vacuum at70° C., to yield off-white Solid 1B1 (4.9 g), which was characterised asfollows:

M_(n)=2,900 daltons; and m=10.7

The mobility of Solid 1B1 was measured as described in the Test Methodherein and μ=1.9×10⁻⁵ cm²V⁻¹s⁻¹ (@160 kV/cm).

The gum-like residue was dried under reduced pressure to yield Solid 1B2(1.03 g) and characterised as follows:

M_(n)=7,000 daltons; and m=25.8;

The mobility of Solid 1B2 could not be obtained by the Test Methodherein, due to the insoluble nature of this material.

EXAMPLE 2

Polymer made without control of molecular weight until reactioncompleted after 68 hours. Preparation of ‘2,4-dimethyl’ polymer bypolymerising bis-(N-chlorophenyl)-2,4-dimethylphenylamine without theuse of endcapping reagent

A reaction flask (250 mL, 5 neck) equipped with overhead stirrer,thermometer and nitrogen line was flame dried under nitrogen. Nickel(II)chloride (0.097 g, 0. 75 mmol), is zinc powder (5.9 g, 90.4 mmol),2,2′-dipyridyl (0.18 g, 1.13 mmol), triphenylphosphine (3.93 g, 15 mmol)and N,N-dimethylacetamide (anhydrous, 75 mL) were charged to thereaction vessel. The mixture was stirred at room temperature for 30minutes after which time a deep red/brown solution was observedindicative of catalyst formation. The temperature was then raised to 80°C. for 30 minutes then bis(4chlorophenyl)-2,4-dimethylphenylamine (10.0g, 29.5 mmol) as a solution in toluene (25 mL) was added to the reactionflask. Heating was continued at 80° C. for 68 hours, after which timethe reaction was deemed complete. The reaction mixture was allowed tocool to room temperature and HCl (conc., 30 mL) added dropwise todestroy the excess zinc. The resulting mixture effervesced.Dichloromethane (100 mL) and water (100 mL) were added to the mixtureand the organic extract was collected. The organic extract was washedsuccessively with water (3×50 mL), NaHCO₃ (saturated solution, 2×50 mL)and water (100 mL), then concentrated under reduced pressure to yieldoff-white Solid 2A. The aqueous phase showed the presence of highermolecular weight material which was insoluble in dichloromethane.Filtration of the aqueous phase afforded Solid 2B which was soluble inhot THF and hot toluene, characterised as follows:

Solid 2B: M_(n)=22,300 daltons and m=82.

Solid 2A was dissolved in THF (50 mL) and precipitated from methanol(700 mL). The resulting precipitate was collected by vacuum filtrationand purified by column chromatography (silica gel), eluting with a 350mL mixture of dichloromethane and hexane (in a respective volume ratioof 3 to 1). Removal of the solvent under reduced pressure followed byprecipitation from THF (50 mL) and methanol (600 mL) yielded the titlepolymer (Solid 2C) as an off-white solid (4.0 g), which wascharacterised as follows:

Solid 2C: M_(n)=5,400 daltons and m=20;

The mobility (i) of Solid 2C was measured as described in the TestMethod herein and i=5.0×10⁻⁷ cm²v⁻¹s⁻¹ (@ 160 kV/cm).

The mobility of Solid 2B could not be obtained by the Test Methodherein, due to the insoluble nature of this material.

TABLE 1 μ (cm²V⁻¹s⁻¹) Example 1 m M_(n) (daltons) @ 160kV/cm Solid 1A11.5 3,100 9.0 × 10⁻⁶ Solid 1B1 10.7 2,900 1.9 × 10⁻⁵ Solid 1B2 25.87,000 NM

TABLE 2 M_(n) μ (cm²V⁻¹s⁻¹⁾ Example 2 m (daltons) @ 160kV/cm Solid 2B 8222,300 NM Solid 2C 20 5,400 5.0 × 10⁻⁷ NM = not measurable.

EXAMPLE 3

Preparation of the “2,4-dimethyl polymer” by polymerising thebis(N-4-chlorophenyl)-2,4-dimethylphenylamine using1-chloro-3-methylbenzene as the end capping reagent.

A reaction vessel (1 liter, 5-neck) was equipped with an overheadstirrer, a nitrogen line and was flame dried under nitrogen. Nickel(II)chloride (0.5 g), zinc powder (30.4 g), 2,2′-dipyridyl (0.9 g),triphenylphosphine (9.9 g) and anhydrous N,N-dimethylacetamide (300 ml)were charged to the reaction vessel. The mixture was stirred at roomtemperature for 30 mins and a deep red/brown solution was observed whichis characteristic of the catalyst. The catalyst solution was warmed to80° C. and then the bis(N-4-chlorophenyl)-2,4-dimethylphenylamine (50.0g) was added to the catalyst solution. The 1-chloro-3-methylbenzene (9.2g) was added over 30 mins via a syringe pump. The reaction wasmaintained at temperature and stirred for 4.5 hours, after which timemore of the 1-chloro-3-methylbenzene (9.2 g) was added. The resultingmixture was stirred for a further 14 hours, to ensure the polymer wascompletely end capped.

The reaction mixture was allowed to cool to room temperature and DCM(100 mL) was added. This mixture was poured into stirring water (300 mL)and hydrochloric acid (10 M, 100 mL) was added dropwise. The resultingmixture effervesced. The organic layer was removed and washedsequentially with sodium hydrogen carbonate solution and several timeswith distilled water. The organic layer was concentrated under reducedpressure to yield a yellow oil. The resulting oil was dissolved in THF(75 mL) and poured into stirring methanol (1.5 liter) to form a yellowsolid (53.8 g). This solid was dissolved in 200 mL of a mixture of DCMand hexane (in a respective ratio of 1 to 1) and purified by columnchromatography (silica gel), eluting with 2.7 liter of a mixture of DCMand hexane (in a respective volume ratio of 1 to 1). The excess solventswere removed, the resulting solid dissolved in THF (75 mL) and thesolution was poured into methanol (1 liter). The precipitate wascollected and dried under vacuum at 70° C., to give yellow flakes (44.5g). This solid was dissolved in 200 mL of a mixture of DCM and hexane(in a respective ratio of 5 to 4) and purified by column chromatography(silica gel), eluting with 2 liter of a mixture of DCM and hexane (in arespective volume ratio of 5 to 4). The excess solvents were removed,the resulting solid dissolved in THF (75 mL) and the solution was pouredinto methanol (1 liter). The resulting precipitate was collected anddried under vacuum at 70° C., to give yellow flakes (41.5 g). This solidwas dissolved in 200 ml of a mixture of DCM and hexane (in a respectiveratio of 10 to 7) and purified by column chromatography (silica gel),eluting with 1.7 liter of a mixture of DCM and hexane (in a respectivevolume ratio of 10 to 7). The excess solvents were removed, theresulting solid dissolved in THF (75 mL) and the solution was pouredinto methanol (1 liter). The resulting precipitate was collected anddried under vacuum at 70° C., to give, as yellow flakes, the titlepolymer (40.5 g), which was characterised as follows:

M_(n)=1400 daltons and m=5.

EXAMPLE 4

Selective Precipitation of the Example 3 to isolate fractions ofdifferent molecular weights.

Fraction 4.1

The product (20 g) from Example 3, was dissolved in THF (400 mL).Methanol (150 mL) was added to form a precipitate/oil and the liquorsdecanted off. The resultant oil (fraction 1) was solidified by theaddition of methanol (100 mL), the precipitate was collected and driedunder vacuum at 70° C. to yield a dark yellow solid (3.9 g). The solidwas dissolved in THF (10 mL) and poured into methanol (100 mL). Theresulting precipitate was collected by vacuum filtration and dried undervacuum at 70° C. to give, as a dark yellow solid (3.7 g), fraction 4.1,which was characterised as follows:

Fraction 4.1: M_(n)=3900 daltons and m=14.

Fraction 4.2

Methanol (75 mL) was added to the remaining liquors decanted fromfraction 4.1 above, to form an oil/precipitate. The liquors weredecanted off. The resultant oil (fraction 4.2) was solidified by theaddition of methanol (100 mL). The dark yellow solid (4.4 g) wascollected, dissolved in THF (10 mL) and poured into methanol (100 mL).The resulting precipitate was collected by vacuum filtration and driedunder vacuum at 70° C. to give, as a yellow solid (4.2 g), fraction 4.2,which was characterised as follows:

Fraction 4.2: M_(n)=3000 daltons and m=10.

Fraction 4.3

Methanol (100 mL) was added to the remaining liquors decanted fromfraction 4.2 above, to form an oil/precipitate. The liquors weredecanted off. The resultant oil (fraction 4.3) was solidified by theaddition of methanol (100 mL). The yellow solid (3.3 9) was collected,dissolved in THF (10 mL) and poured into methanol (100 mL). Theresulting precipitate was collected by vacuum filtration and dried undervacuum at 70° C. to give, as a yellow solid (3.2 g), fraction 4.3, whichwas characterised as follows:

Fraction 4.3: M_(n)=2000 daltons and m=7.

The electrical performance of different fractions is shown in Table 3.

TABLE 3 M_(n) μ (cm²V⁻¹s⁻¹⁾ Example m (daltons) @ 160kV/cm 3 5 1,4001.22 × 10⁻⁵ Fraction 4.1 14 3,900 8.42 × 10⁻⁵ Fraction 4.2 10 3,000  4.5× 10⁻⁵ Fraction 4.3 7 2,000  1.4 × 10⁻⁵

Example 4.1 to 4.3 illustrates that successive molecular weightfractions isolated from a 25 crude polymeric CTM exhibit higher mobilitythan the crude polymer (Example 3). Thus polymers isolated by selectiveprecipitation exhibit improved properties as CTM.

EXAMPLE 5 Part A

Preparation of ‘2,4-Dimethyl’ Polymer by Polymerisingbis(N-Chlorophenyl)-2,4-dimethylphenylamine Without the use ofEnd-capping Reagent

A reaction flask (1 L, 5-neck) equipped with overhead stirrer,condenser, thermometer and nitrogen line was flame dried under nitrogen.Nickel(II) chloride (0.79 g, 6.1 mmol), zinc powder (48.8 g, 747 mmol),2,2′-dipyridyl (1.44 g, 9.22 mmol), triphenylphosphine (9.52 g, 58.4mmol) and N,N-dimethylacetamide (anhydrous, 620 mL) were charged to thereaction vessel. The mixture was stirred at room temperature for 30minutes, then at 80° C. for a further 30 minutes, after which time adeep red/brown solution was observed indicative of catalyst formation.Bis-(4-chlorophenyl)-2,4-dimethylphenylamine (15.0 g, 43.8 mmol) wasadded to the reaction flask, washing in with furtherN,N-dimethylacetamide (anhydrous, 20 mL). Heating was continued at 80°C. for 5 hours, after which time the reaction was deemed complete, byHPLC analysis. The reaction mixture was allowed to cool to roomtemperature then poured into toluene (1 L). HCl (conc., 400 mL) wasadded dropwise to the organic solution, with stirring, to destroy theexcess zinc. The resulting mixture effervesced. The organics wereseparated and washed successively with water (400 mL), sodium hydrogencarbonate (sat. soln., 2×400 mL) and water (400 mL), then dried (MgSO₄).The solvents were concentrated under reduced pressure to yield a viscousyellow residue. The residue was dissolved in THF (100 mL) and addeddropwise to methanol (500 mL), with stirring. The resultant precipitatewas collected by vacuum filtration, then dried under vacuum at 70° C.,to yield the title compound (Solid 5A) as a yellow solid (60 g). Mn=3400daltons; Mw=6900 daltons; m=12.5; and Cl=0.6% w/w.

Part B

Fractionation of ‘2,4-Dimethyl’ Polymer From Polymersiation ofbis(N-Chlorophenyl)-2,4-dimethylphenylamine without the Use ofEndcapping Reagent

Solid 5A isolated in Part A was fractionated to obtain fractions ofnarrower Mw distribution. Thus, Solid 5A (50.0 g) was dissolved in THF(200 mL) and methanol added dropwise in a process of fractionalprecipitation. Methanol was added dropwise (see Table 4 for quantities)until the solution maintained a cloudy appearance. After each methanoladdition, the solution mixture was allowed to settle then the top liquorlayer was decanted off and further methanol added to repeat the process.The bottom cloudy layer was treated with excess methanol (100 mL) toencourage precipitation of the product. Each precipitate was collectedby vacuum filtration.

TABLE 4 Fraction Total methanol added, (mL) {fraction (1/1)} 45 ½ 50(+5) ⅓ 60 (+10) ¼ 70 (+10) ⅕** 76 (+10) **fraction obtained afterremoval of all solvent under reduced pressure.

Fractions {fraction (1/1)} and /½ were recombined and fractionated fromTHF and acetone.

Thus, the fractions were dissolved in THF (200 mL) and the fractionationprocess repeated as described earlier (see Table 5).

TABLE 5 Fraction Total acetone added, (mL) {fraction (2/1)}  80{fraction (2/2)}  95 (+15) ⅔ 130 (+35) {fraction (2/4)}** 130 (+35)**fraction obtained after removal of all solvent under reduced pressure.

Of all the fractions obtained, only fractions ⅓, ¼, ⅕, ⅔ and {fraction(2/4)} were purified by column chromatography (silica gel). Eachfraction was dissolved in a dichloromethane/hexane mixture (100 mL;1:1), adsorbed onto the column and eluted with a dichloromethane/hexanemixture (2:1, 500 mL; then 3:1, 500 mL). Removal of the solvent underreduced pressure followed by precipitation from THF (50 mL) and methanol(250 mL), as described earlier, yielded the compounds as colourlesssolids (see Table 6).

TABLE 6 GPC % Cl Weight Fraction (daltons) (w/w) (g) ⅓ Mw 5700; Mn 3700;m 13.6 0.7 5.1 ¼ Mw 4000; Mn 3000; m 11.0 0.7 2.5 ⅕ Mw 1700; Mn 1100; m4.0 0.5 4.0 ⅔ Mw 7200; Mn 5300; m 19.6 0.7 4.4 {fraction (2/4)} Mw 3600;Mn 2200; m 8.1 0.7 7.5

The electrical results for each of the purified fractions are given inTable 7.

TABLE 7 E_(⅞) μ (cm²V⁻¹s⁻¹) Fraction m (μJcm⁻²) V_(r)(V) @ 160kV/cm ⅕4.0 n/a* −190 1.6 × 10⁻⁶ {fraction (2/4)} 8.1 0.42 −44 2.4 × 10⁻⁵ ¼ 11.10.39 −34 4.1 × 10⁻⁵ ⅓ 13.6 0.42 −43 8.1 × 10⁻⁵ ⅔ 19.6 0.45 −39 1.8 ×10⁻⁵ *NoE_(⅞ value could be measured for fraction ⅕ since it did not discharge to −100V.)

EXAMPLE 6 Isolation of Mw Fractions by Soxhlet Extraction

Part A Preparation of 2,4-dimethyl polymer by polymerisingbis(N-chlorophenyl)-2,4-dimethylphenylamine using1-chloro-3-methylbenzene as the end capping reagent.

A reaction flask fitted with overhead stirrer, condenser, thermometerand nitrogen line was flame dried under nitrogen. Nickel (II) chloride(0.06 g, 0.6 mmol), zinc (5.0 g, 75.0 mmol), 2,2′-dipyridyl (0.14 g, 0.9mmol), triphenylphosphine (1.6 g, 6.0 mmol) and N,N-dimethylacetamide(90 cm³) were charged to the reaction vessel. The mixture was stirred atroom temperature for 30 minutes after which time a deep red/brownsolution was observed indicative of catalyst formation. The catalyst waswarmed to 74° C. and bis(4-chlorophenyl)-2,4-dimethylphenylamine (8.35g, 25.0 mmol) and 1-chloro-3-methylbenzene (1.6 g, 12.5 mmol) were addedto the reaction mixture. The reaction mixture was maintained at thistemperature for 6 hours, after which time further1-chloro-3-methylbenzene (0.3 g, 20% of original charge) was added. Thereaction mixture was maintained at 74° C. for a further 16 hours toensure the polymer was completely end capped.

The reaction mass was allowed to cool to room temperature anddichloromethane (100 cm³) added and the reaction mixture filtered. Thefiltrate was washed with HCl (1M, 50 cm³) and dilute NaHCO₃ (200 cm³)and dried with MgSO₄. The organic extract was concentrated under reducedpressure to a yellow oil. The resulting yellow oil was dissolved in THF(50 cm³) and precipitated into methanol (400 cm³). The precipitate wascollected by suction filtration, washing with methanol (3×100 cm³), thendried under vacuum at 70° C. to yield the title product as an off-whitepowder (5.02 g). Mn=1300 daltons; Mw=2250 daltons; m=4.

Part B Repeat of Part A to yield the title product as an off whitepowder (4.53 g). Mn=860 daltons; Mw=1500 daltons; m=2.5.

Portions of the isolated crude products (approx 0.5 g, accuratelyweighed) from Part A or Part B were placed into an extraction thimbleand extracted with a specified solvent under reflux for 24 hours. Eachresidue was dried, weighed and analysed by GPC. (see Tables 8 and 9)

TABLE 8 Analysis of Residues from Part A before & after SolventExtraction Solvent Bpt (° C.) Mn Mw m Polydispersity Before N/A 13002250 4.0 1.74 extraction n-Hexane 69 2670 2400 9.0 1.30 Pet ether 602650 2900 9.0 1.30 (60-80° C.) Methyl 62 2400 2400 8.0 1.35 pentanen-Octane 125 2200 2430 7.5 1.43 Heptane 98 2000 1900 7.0 1.50 2-Propanol82 1800 1900 6.0 1.50 Ethanol 78 1700 1500 6.0 1.60 n-Butanol 116 17001500 5.5 1.60

TABLE 9 Analysis of Residues from Part B before & after SolventExtraction Solvent Bpt (° C.) Mn Mw m Polydispersity Before N/A 860 15002.5 1.75 extraction MTBE 55 1700 2490 5.5 1.48 Acetone 56 1370 2040 4.01.49 Methanol 65 940 1590 3.0 1.69

Aspects of the Invention may be Summarised as in the Following Clauses

1. A polymeric material comprising at least one repeat unit, the or each(if more than one) repeat unit consisting substantially of a moiety ofFormula D:

in which:

Y¹ represents, independently if in different repeat units, N, P, S, Asand/or Se preferably N;

Ar¹ and Ar² which may be the same or different, represent, independentlyif in different repeat units, a multivalent (preferably bivalent)aromatic group (preferably mononuclear but optionally polynuclear)optionally substituted by at least one optionally substitutedC₁₋₄₀-carbyl-derived groups and/or at least one other optionalsubstituent, and Ar³ represents, independently if in different repeatunits, a mono or multivalent (preferably bivalent) aromatic group(preferably mononuclear but optionally polynuclear) optionallysubstituted by at least one: optionally substituted C₁₋₄₀-carbyl-derivedgroup and/or at least one other optional substituent, characterised inthat, after polymerisation, the polymeric material is treated by aisolation means to isolate a molecular weight fraction which iseffective as a charge transport material.

2. A polymeric material as in clause 1, which comprises a substancerepresented by the following formula:

wherein

Ar¹, Ar², Ar³ and Y¹ represent, independently in each case, thosegroup(s) and/or atom(s) as claimed in claim 1;

n represents an integer from 3 to about 500;

R¹ & R² represent, independently, a terminal group as described herein;

R³ represents H or a terminal group which is inert to coupling underpolymerisation conditions, such as alkyl or aryl.

3. A polymeric material as in any preceding clause, in which Ar¹, Ar²and Ar³ comprise, independently if in different repeat units, at leastone optionally substituted heterocyclic and/or benzenoid ring whichcomprises an aromatic moiety.

4. A polymeric material as in any preceding clause, in which Ar¹, Ar²and Ar³ comprise, independently if in different repeat units, a bivalentaromatic C₆₋₄₀-hydrocarbyl.

5. A polymeric material as in any preceding clause, which comprises asubstance represented by the following formula:

wherein

R¹, R² & n represent, independently if in different repeat units, thosegroups or values described herein, R³ only being present when the ringto which it is attached is not itself attached to another repeat unit;

R³ represents H or a terminal group which is inert to coupling underpolymerisation conditions, such as alkyl or aryl;

a & b represent, independently in each case, 0 or an integer from 1 to4;

c represents, independently in each case, 0 or an integer from 1 to d(where d is 6 minus the valence of the aromatic group), preferably 0 to5;

n represents an integer from 4 to about 200; and

R⁴, R⁵ & R⁶ represent, independently in each case, optionallysubstituted C₁₋₁₅-alkyl and/or at least one optional substituent.

6. A polymeric material as in any preceding clause, in which theterminal group(s) comprise, independently if in different repeat units,at least one optionally substituted C₁₋₄₀-hydrocarbyl group each ofwhich is substantially incapable of undergoing chain extension orcross-linking under the conditions of polymerisation.

7. A polymeric material as in any preceding clause, in which theterminal group(s) comprise, independently if in different repeat units,at least one group selected from C₁₋₃₀-alkyl, C₆₋₃₆-aryl andC₇₋₃₆-aralkyl each of which is substantially incapable of undergoingchain extension or cross-linking under the conditions of polymerisation.

8. A polymeric material which is obtainable and/or obtained by at leastone of the processes as in any of clauses 28 to 30.

9. A polymeric material substantially as described herein with referenceto the Examples and Tables herein.

10. A composition comprising an inert diluent, optionally substantiallyelectroreprographically inert, and, optionally in a substantially pureform, at least one polymeric material as claimed in any preceding claim.

11. A composition as in clause 10, in which the diluent is selected fromat least one of polyamide, polyurethane, polyether, polyester, epoxyresin, polyketone, polycarbonate, polysulfone, vinyl polymer,polystyrene, polyacrylamide, copolymers thereof and mixtures thereof.

12. A composition as in clause 10 or 11, which has a T_(g) which iswithin about 50° C. of the T_(g) of the diluent resin.

13. A composition as in any of clauses 10 to 12, which comprises the atleast one polymeric material as claimed in any of claims 1 to 9 in atotal amount from about 8% to about 100% by total mass of thecomposition.

14. A composition as in clause 13, which comprises the at least onepolymeric material in a total amount from about 10% to about 75% bytotal mass of the composition.

15. A composition as in clause 13 or 14, which comprises the at leastone polymeric material in a total amount from about 15% to about 50% bytotal mass of the composition.

16. A composition comprising at least one polymeric material as in anyof clauses 10 to 15, the composition being substantially as describedherein and/or exhibiting the properties described herein, with referenceto any of the Examples and/or Tables herein.

17. A device and/or a component for a device comprising at least onepolymeric material as in any of clauses 1 to 9 and/or composition as inany of clauses 10 to 16.

18. A device and/or component as in clause 17, which comprises at leastone: electroreprographic device, photo-conductive member for anelectroreprographic device, component of an electroreprographic device,and/or consumable for use with and/or in an electroreprographic device.

19. A device, photo-conductor, component and/or consumable as in clause18, where the device is selected from at least one: photocopier, printer(optionally laser printer), fax machine, scanner and multipurposedevices for copying, faxing and/or scanning.

20. A device, photo-conductor, component and/or consumable as in clause18 or 19, comprising at least one photosensitive drum and/orphotosensitive belt.

21. A device and/or component as in clause 17, which is selected from atleast one of the following devices and/or can be used in at least one ofthe following applications: electroluminescent device, organic lightemitting device (OLED); semi-conductor device; photoconductive diode;light emitting diode (LED); metal-semiconductor junction; p-n junctiondiode; solar cell and/or battery; photovoltaic device; photodetector,optical sensor; phototransducer; bipolar junction transistor (BJT),hetero-junction bipolar transistor and/or other switching transistor;field effect transistor (FET); charge transfer device; laser; p-n-p-nswitching device; optically active EL device; thin film transistor(TFT); organic radiation detector; infra-red emitter; tunablemicrocavity for variable output wavelength; telecommunications deviceand/or application; optical computing device; optical memory device;general design of detector and/or sensor; chemical detector; any deviceand/or application which requires polymeric material which exhibits atleast one of the following properties: polymeric conduction, polymericphoto-conduction, substantial conjugation over the polymer, polymericsemi-conduction, high carrier mobility, compatibility with binders,improved solubility, high durability and/or high resistivity undoped;and any suitable combinations thereof in the same device and/orcomponent.

22. A method for making a composition as in any of clauses 10 to 16, bymixing at least one polymeric material as claimed in any of claims 1to 9with an inert diluent.

23. A method for making a charge transport layer (CTL) comprisingcoating a substrate with a composition as in any of clauses 10 to 16,and/or at least one polymeric material as in any of clauses 1 to 9optionally in at least one layer.

24. A method of making a device and/or component as in any of clauses 17to 21, comprising the step of forming on a substrate at least one chargetransport layer (CTL) which comprises a composition as in any of clauses10 to 16, and/or at least one polymeric material as in any of clauses 1to 9.

25. Use of a composition as in any of clauses 10 to 16, and/or at leastone polymeric material as in any of clauses 1 to 9 as a charge transportmaterial.

26. Use of a composition as in clauses 10 to 16, and/or at least onepolymeric material as in any of clauses 1 to 9, in the manufacture of adevice and/or component as in any of clauses 17 to 21.

27. Use of a composition as in any of clauses 10 to 16, and/or at leastone polymeric material as in any of clauses 1 to 9, in a device and/orcomponent as in any of clauses 17 to 21, for the purpose of transportingcharge and/or improving electroreprographic and/or electroluminescentperformance.

28. A process for preparing a polymeric material as in any of clauses 1to 9, comprising after polymerisation an isolation method comprisingeither sequentially or simultaneously the steps of:

a) solvent extraction with one or more solvents in which the desiredfraction to be isolated has a differential solubility from the unwantedfraction in the polymer mixture.

b) solid/liquid extraction from a suitable solvent, optionally bySoxhlet extraction and/or slurry extraction;

c) filtration;

d) chromatography,

e) differential separation of the fraction as a gel and/or particulatemass, optionally by differential: flocculation, coagulation, saltingout, aggregation, agglomeration and/or precipitation of the fractionfrom the crude polymer and/or a combination of these methods.

f) ion exchange, optionally by derivatisation of a suitable salt on thecentral atom of the polymer repeat unit and then passing the saltthrough the ion-exchange column.

g) wiped film evaporation.

h) melt crystallisation and/or zone refining.

i) application of ultrasound; and/or

j) osmotic methods.

29. A process as in clause 28, in which the isolation method comprisessolvent extraction with at least one solvent selected from the followingeach optionally substituted: alkanes, alkyl amines, aromatic compounds,ethers and/or mixtures thereof.

30. A process as in clause 29, in which the solvent is selected from:n-octane, heptane, n-hexane, cyclohexane, methylpentane, n-butanol,n-propanol, 2-propanol, ethanol, methanol, acetone, a mixed alkanepetroleum ether with boiling range 60-80° C., methyl tertiary-butylether, a high boiling mixed alkane available under the trade nameIsopar; and/or mixtures thereof.

What is claimed is:
 1. A process, comprising: isolating a chargetransport material, from a polymer comprising repeat units that areindividually represented by the following Formula X

in which Y represents P or N; Ar¹ and Ar² represent a bivalent aromaticgroups; Ar³ represents a monovalent aromatic group; and the repeat unitsof Formula X are the same or different.
 2. A process for obtaining animproved charge transport material, comprising: isolating from a firstcharge transport material which is a polymer comprising repeating unitswhich are individually represented by the following Formula X

wherein Y represents P or N, Ar¹ & Ar² represent bivalent aromaticgroups; Ar³ represent a monovalent aromatic group; and the repeat unitsof Formula X are the same or different, the improved charge transportmaterial having a molecular weight fraction with improved chargetransport properties.
 3. The process according to claim 1 in which Ar¹,Ar² and Ar³ comprise benzenoid rings which are optionally substituted.4. The process as claimed in claim 1 in which said charge transportmaterial possesses reactive terminal groups permitting furtherpolymerisation to be carried out.
 5. The process according to claim 1which comprises a step of partially precipitating the said chargetransport material from a solution of said polymer in a solvent toobtain at least one molecular weight fraction thereof which constitutesat most 50% by weight of the polymer, (including low oligomers),originally present.
 6. The process of claim 1 in which said chargetransport material is isolated by dissolving the polymer in a solvent,precipitating the least soluble (highest molecular weight) fraction andthen recovering a fraction of greater solubility from the remainingsolution.
 7. The process of claim 1 in which the said charge transportmaterial is separated by dissolving the original polymer in a solvent,precipitating the least soluble fraction leaving a substantial quantityof lower molecular weight material in solution, and either precipitatinga further, medium molecular weight fraction from the solution orseparating medium molecular weight material from the least solublefraction.
 8. The process of claim 5 in which undesired low molecularweight molecules, which may be present, remain in the solution while animproved charge transport material fraction is recovered.
 9. The processof claim 5 in which multiple fractions are recovered by causingprecipitation by cooling the solution and collecting successivefractions in the course of cooling or by evaporating the solvent fromthe solution, and collecting successive fractions.
 10. The process ofclaim 9 in which the fractions are separated by a process whichcomprises differential precipitation by adding a precipitant to asolution of the polymer and collecting successive fractions atincreasing concentrations of the precipitant.
 11. The process as claimedin claim 10 in which the precipitant is a liquid miscible with thesolvent but in which the polymer is sparingly soluble.
 12. The processas claimed in claim 5 in which the solvent is selected from THF,dioxane, dichloroethane, trichloroethane, dichloroethylene,trichloroethylene, toluene and dichlorobenzene.
 13. The process asclaimed in claim 1 in which a solid polymer is extracted to form asolution of a molecular weight fraction thereof.
 14. A charge transportmaterial, comprising: units represented by Formula 1 AX_(m)B  Formula 1wherein X represents groups, which may be the same as or differ fromother groups, represented by the following formula X:

wherein Y represents P or N, Ar¹ & Ar² represent bivalent aromaticgroups, and Ar³ represents a monovalent aromatic group; A & B are anygroups terminating the chain, and m is 4to 50; and wherein said chargetransport material is isolated from a polymer comprising repeat unitsthat are individually represented by the Formula X.
 15. A chargetransport material produced by the process according to claim
 7. 16. Adevice comprising the charge transport material of claim
 14. 17. Thecharge transport material of claim 14, wherein said groups terminatingthe chain include hydrogen.
 18. The charge transport material of claim14, wherein said groups terminating the chain include chlorine, bromineor iodine.
 19. The charge transport material of claim 14, wherein saidgroups terminating the chain are leaving groups.
 20. The chargetransport material of claim 14, wherein said groups terminating thechain are end capping groups.
 21. The process of claim 1 which comprisesa step of partially precipitating said charge transport material from asolution of said polymer in a solvent to obtain at least one molecularweight fraction thereof which constitutes at most 75% by weight of thepolymer, (including low oligomers), originally present.
 22. The processof claim 1 which comprises a step of partially precipitating said chargetransport material from a solution of said polymer in a solvent toobtain at least one molecular weight fraction thereof which constitutesat most 90% by weight of the polymer, (including low oligomers),originally present.
 23. The process of claim 7 wherein at least 10% oflower molecular weight material is left in the solution.
 24. The processof claim 7 wherein at least 20% of lower molecular weight material isleft in the solution.
 25. The process of claim 7 wherein at least 60% oflower molecular weight material is left in the solution.